This invention relates to the coloration of dental restorations and more particularly to methods of altering the coloring of previously prepared dental restorations to obtain a matching or otherwise desired color. By dental restoration herein is meant any configuration of material designed to improve the appearance or function of a tooth or teeth. This would include fillings, bridges, crowns, dentures, etc.
Present techniques for obtaining the desired color of restorations involve either having the coloring agent incorporated into the material itself at the time of formulation, or applying the coloring agent as a coating after the restoration has been manufactured. Typical of proposed methods of incorporating the coloring agent within the restoration material prior to preparing the restoration is shown in U.S. Pat. Nos. 4,433,959 and 4,563,153. U.S. Pat. No. 4,481,227 shows a method of adding the coloration agent to restoration after the latter is prepared.
Both of these methods have severe drawbacks. When the coloring agent is incorporated into the material, typically in the laboratory where the restoration is manufactured, it is difficult if not impossible to match the color and shading of the restoration perfectly with the tooth on which the crown is to be mounted. Coating techniques also generally require preparation in the laboratory with the similar difficulty to obtain an acceptable, if not a perfect, match. In both techniques, it is not possible or convenient to alter the color without repeating the complete procedure involved.